Process for the washing and purifying of molten metals

ABSTRACT

A process for washing and purifying molten metals in continuous casting operations includes injecting a flash gas on the molten surface of the continuously moving workpiece in such a manner that the drawn off gases prevent the admission of air.

United States Patent Inventor Manfred Schrage Dudenhofen near Offenbach,Germany Appl. No. 679,684 Filed Nov. 1, 1967 Patented Feb. 16, 1971Assignee Messer Griesheim, GmbH Frankfurt am Main, Germany a corporationof Germany Priority Nov. 12, 1966 Germany M 71642 PROCESS FOR THEWASHING AND PURIFYING OF MOLTEN METALS 6 Claims, 2 Drawing Figs.

U.S. C1 .l 164/82, 164/55, 164/66 Int. Cl 822d 11/00 Field of Search 164/ 66,

[56] References Cited UNITED STATES PATENTS 3,395,750 10/1968 Keene164/259 3,300,824 III 967 Ross 164/66 2,889,596 6/1959 Savage et al164/283 3,224,051 12/1965 Brown, Jr. et all 164/66 963,973 7/1910Wright. 3,411,566 ll/l968 Astrov etal. l64/55X 3,392,009 7/1968 Holmeset al. 164/66X FOREIGN PATENTS 1,031,317 6/1966 Great Britain.

Primary Examiner-Charles W. Lanham Assistant Examiizer-V. K. RisingAttorney-Connolly & Hutz ABSTRACT: A process for washing and purifyingmolten metals in continuous casting operations includes injecting aflash gas on the molten surface of the continuously moving workpiece insuch a manner that the drawn off gases prevent the admission ofair.

PATENTEU FEB 1 s |97| BACKGROUND OF THE INVENTION The invention relatesto a process for the washing and purifying of molten metals with respectto continuous casting processes by the injection of gases or gasmixtures.

It is known to treat molten metal by injecting gases, for instance byinjecting oxygen in refining or by injecting argon on melts located inthe casting ladle fo'r decontamination purposes. Furthermore, it iscustomary during the pouring ihto the cast iron mold in continuouscasting installations to piotect the melt surface and the castingcurrent against air admission by means of an argon screen or mist.

The utilization of both processes has the disadvantage that they must beundertaken separately, in two steps, i.e. in the casting ladle and inthe continuous casting mold, if the decontamination effect is not to belost during pouring.

SUMMARY or INVENTION The object of the invention is to eliminate theabove disadvantages and to provide a process which combines an effectivewashing of the liquid metal with an effective casting protection.

Inaccordance with this invention the flash gas is blown on the moltensurface of the continuously moving work piece in such a manner that thedrawing off gases effect a casting protection against air admission. Alance may be suitably used for the injection ofthe flash gas.

The desired exchange of material takes place at the contact surfacesbetween gas and melt. The gas rising from the melt surfacesimultaneously protects the melt surface and casting current. Aconsiderable advantage of this process lies particularly in that themelt can be very effectively decontaminated by the continuously renewingsurfaces which form in the castiron mold.

An arrangement for the carrying out the inventive process 7 in anadvantageous manner, includes a lance for the injection of the flash gasbetween the distribution groove of or casting ladle for the moltensubstance and the cast-iron mold. Between the distribution groove orladle and the cast-iron mold, a box or bellows like protective devicecan also be arranged for obstructing or baffling the gases drawn offthrough an outlet. The protective device can be placed under more orless intensely reduced pressure, to assure that the gases rising fromthe melt surface are drawn off. In this simple and advantageous mannerthe decontaminating reaction is simultaneously intensified by thecombination of flash gas process and reduced pressure. I

In the inventive process the inert or reactive flash gas can be utilizedas a carrier for gaseous, liquid or solid additives.

THE DRAWINGS FIG. I shows a distribution lance; and

FIG. 2 shows an arrangement protective device.

DETAILED DESCRIPTION grove'with cast-iron mold and according to FIG. 1with a melt and gas takes place in the contact zone 5. The rising gasesprotect both the melt surface as well as the casting current and preventthe admission of air by thereby acting as a shield.

The space between distribution groove I and cast-iron mold 2 can,according to FIG. 2, be further surrounded by a box or enhance thecasting protection.

Furthermore, reduced pressure can be provided at the discharge opening 7of the casting protection device, so that the drawn off gases arespeedily drawn off and so that the decontamination reaction isaccelerated by the combination of the reduced pressure and blowing.

The invention is, ofcourse, in no way limited to the embodimentsdescribed above and illustrated in the drawing, since variousmodifications are possible without deviating from the scope of theinvention. Thus, flash gas, for example, can be utilized as a carrierfor certain solid, liquid or gaseous additives.

Iclaim:

I. In a process for flushing, purifying and degassing molten metal witha gas stream in a continuous casting installation including a castingladle for the molten metal and there being beneath said casting ladle acast-iron mold for continuously forming a workpiece, comprisingdirecting the gas stream into the surface of the molten metal in saidmold below said ladle, penetrating the gas stream into the molten metala depth for flushing, purifying and degassing the same while the castingoperation is taking place, drawing off the gas from the molten metalwhile the casting operation is taking place, creating a shield with thedrawn-off gas to prevent the admission of air to the surface of themolten metal, the gas being directed by a lance between the ladle forthe molten substance and the castiron mold, baffling the drawn off gasby means of a protective device disposed between the ladle and cast-ironmold and said device having a gas outlet therein, and maintaining saiddevice under reduced pressure.

2. In a process as set forth in claim I wherein the gas is used as anadditive carrier.

3. A process for flushing, purifying and degassing molten metal with agas stream in a continuous casting installation including a castingladle for the molten metal and there being beneath said casting ladle acast-iron mold for continuously forming a workpiece, comprisingdirecting the gas stream into the surface of the molten metal in saidmold belowsaid ladle. penetrating the gas stream into the molten metal adepth for flushing, purifying and degassing the same while the castingoperation is taking place, applying mechanical means for drawing off thegas from the molten metal while the casting operation is taking place,and creating a. shield with the drawnoff gas to prevent the admission ofair to the surface of the molten metal.

4. In a process as set forth in claim 3 including baffling the drawn offgas by means of a protective device disposed between the ladle andcast-iron mold and said device having a gas outlet therein.

5. A process for flushing, purifying and degassing molten metal with agas stream in a continuous casting installation including a castingladle for the molten metal and there being beneath saidcasting ladle acast-iron mold for continuously forming a workpiece, comprisingdirecting the gas stream into the surface of the molten metal in saidmold below said ladle, penetrating the gas stream into the molten metala depth for flushing, purifying and degassing the same while the castingoperation is taking place, drawing off the gas from the molten metalwhile the casting operating is taking place, creating a shield with thedrawn-off gas to prevent the admission of air to the surface of themolten metal, providing a bellows formation between the ladle and moldwith the drawn-off flowing out of the bellows formation, and utilizingthe bellows formation to baffle the drawn-off gas flowing therefrom.

6. In the process as set forth in claim 5 including applying mechanicalmeans to the bellows formation for drawing off the gas from the moltenmetal.

2. In a process as set forth in claim 1 wherein the gas is used as anadditive carrier.
 3. A process for flushing, purifying and degassingmolten metal with a gas stream in a continuous casting installationincluding a casting ladle for the molten metal and there being beneathsaid casting ladle a cast-iron mold for continuously forming aworkpiece, comprising directing the gas stream into the surface of themolten metal in said mold below said ladle, penetrating the gas streaminto the molten metal a depth for flushing, purifying and degassing thesame while the casting operation is taking place, applying mechanicalmeans for drawing off the gas from the molten metal while the castingoperation is taking place, and creating a shield with the drawn-off gasto prevent the admission of air to the surface of the molten metal. 4.In a process as set forth in claim 3 including baffling the drawn offgas by means of a protective device disposed between the ladle andcast-iron mold and said device having a gas outlet therein.
 5. A processfor flushing, purifying and degassing molten metal with a gas stream ina continuous casting installation including a casting ladle for themolten metal and there being beneath said casting ladle a cast-iron moldfor continuously forming a workpiece, comprising directing the gasstream into the surface of the molten metal in said mold below saidladle, penetrating the gas stream into the molten metal a depth forflushing, purifying and degassing the same while the casting operationis taking place, drawing off the gas from the molten metal while thecasting operating is taking place, creating a shield with the drawn-offgas to prevent the admission of air to the surface of the molten metAl,providing a bellows formation between the ladle and mold with thedrawn-off flowing out of the bellows formation, and utilizing thebellows formation to baffle the drawn-off gas flowing therefrom.
 6. Inthe process as set forth in claim 5 including applying mechanical meansto the bellows formation for drawing off the gas from the molten metal.